Reversible tie-back tool

ABSTRACT

Disclosed herein is a reversible tie-back tool which may be built to run on a reclamation tubing string in order to provide a means to tie back into a tubing string that has been backed off within a liner. The reversible tie-back took insures screwing back into the fish or lost tubing string without damaging either the exposed box or pin of the plugged tubing string or of the reversible tie-back tool allowing a pressure tightening of the fish and reclamation tubing string from the surface.

United States Patent [191 Darby 1 JuneS, 1973 {54] REVERSIBLE TIE-BACK TOOL [75] Inventor: Embree L. Darby, Lafayette, La.

[73] Assignee: Cities Service Oil Company, Tulsa,

Okla.

[22] Filed: Dec. 23, 1971 [211 Appl. No.: 211,448

[52] US. Cl. ..294/86.34, 166/98, 294/86.l,

294/86.l2 [51] Int. Cl. ..E21b 31/02 [58] Field of Search ..294/86.l, 86.12,

294/86.22, 86.34; 24/263 D, 263 DF; 166/98, 124, 315; 285/27, 28, 30, 31

[561 References Cited UNITED sTATEs PATENTS 3,083,767 4/1963 Brown ..294/86.34 X

all;

.....294/86.34 X Le Bus ..294/86.22

2,904,114 9/1959 Webb et al. 2,275,911 3/1942 Primary ExaminerEvon C. Blunk Assistant Examiner-Johnny D. Cherry Attorney-J. Richard Geaman 57 ABSTRACT 3 Claims, 1 Drawing Figure REVERSIBLE TIE-BACK TOOL BACKGROUND OF THE INVENTION The present invention relates to a reversible tie-back tool. More particularly, the apparatus of the present invention comprises a tie-back tool which may be utilized in combination with a reclamation tubing string in order to envelop a lost tubing string or fish within a wellbore liner and allow for pressure tightening thereof the reclamation tubing string therewith the lost tubing string.

During work-over operations it is often encountered where the tubing string is lost within the wellbore liner at a considerable depth within the wellbore. It is desired to have assistance in getting the tie-back tool over the top of a fish while protecting the box or pin exposed at the end of the tie-back tool and the fish. A reversible tie-back tool is required incorporating the features that the tool will accommodate either a box or pin left in the hole and having a cut lip guide skirt which may be installed on either end of the tool prior to running in the hole to assist in getting into the top of the liner and over the top of the fish while protecting the tie-back connection while running in the hole. The skirt should be useful in various casing sizes with a tie-back string that passes along side the top of the fish and allows the tool to be made in the machine shop having particular dimensions and thread types designed to fit the requirements of the tie-back job.

It is an object of the present invention to provide a reversible tie-back tool.

It is a further object of the apparatus of the present invention to provide a reversible tie-back tool which may be incorporated in order to provide a means for obtaining a tight connection with a lost tubing string or fish contained within a wellbore liner.

It is still a further object of the present invention to provide the means for a back-off on an exposed box or pin through one reversible tie-back tool such that any lost tubing or fish contained within a wellbore may be readily tied back through introduction of a tie-back string containing the reversible tie-back tool.

With these and other objects in mind, the present invention may be more readily understood through referral to the accompanying drawing and following discusslon.

SUMMARY OF THE INVENTION The objects of the present invention are accomplished through utilization of a reversible tie-back tool for locating and securing a fish within the liner of a wellbore. The reversible tie-back tool comprises a skirt having an outside diameter of less than the inside diameter of the liner, an inside diameter greater than the outside diameter of the fish and being internally threaded on one end. The tie-back tool further comprises a main housing having a central passageway therethrough its axial center, connecting each end thereof and an outside diameter similar to that of the threaded skirt and being threaded at two diammetrically opposed positions along its circumferential surface so that either threaded surface may be received by the threads of the skirt and having a threaded box, with an outside diameter of less than the inside diameter of the skirt, turned upon one end of the main housing and a threaded pin, having an outside diameter less than the inside diameter of the skirt, turned upon the opposing end of the main housing from that of the threaded box. Said box and pin being internally and externally threaded respectively to receive the threads of the fish with one end of the main housing being turned within the skirt to form a reversible tie-back tool. It is preferred that the threaded skirt be tapered at its unthreaded end to facilitate the envelopment of the fish and that the central passageway passing therethrough the main housing be circular and have a similar diameter to that of the internal diameter of the fish.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention may be more readily understood by referral to the accompanying drawing in which a preferred embodiment of the reversible tieback tool is disclosed.

DETAILED DESCRIPTION OF THE INVENTION The criteria of the present invention provides a design of a reversible tie-back tool which accommodates either a box or pin left in a hole exposed as a fish from the lost tubing string. The many embodiments which the reversible tie-back tool may encompass are most specifically defined by referral to the accompanying FIGURE in which a preferred embodiment of reversible tie-back tool is depicted. In particular, a skirt 14 is provided having an outside diameter less than the inside diameter of a wellbore liner contained within the wellbore through which the skirt is slipped, having an inside diameter greater than the outside diameter of the fish or end of the lost tubing string contained within the wellbore, neither of which are depicted within the FIG- URE in order to more easily define the particular design of the apparatus of the present invention. A main housing 12 is provided having a central passageway 26 therethrough its axial center connecting each end thereof and having an outside diameter similar to that of the threaded skirt l4 and being threaded at two diammetrically opposed positions 20-28 along its circumferential surface so that either threaded surface may be received by the threads 18 of the skirt and having a threaded box 30, containing internal thread 32, with an outside diameter less than the inside diameter of the skirt 14, turned uponone end of the main housing 12 and a threaded pin 22, containing external threads 24 thereon, and having an outside diameter of less than the inside diameter of the skirt 14 turned upon the opposing end of the main housing from that of the threaded box 30. The threaded box 30 and the pin 22 are internally and externally threaded by threads 32 and 24, respectively, to receive the threads of the fish. One end of the main housing 12 is turned within the skirt 14 such that the external threads 20 of the main housing mesh with the internal threads 18 of the skirt 14 to form a reversible tie-back tool 10 of the present invention.

It is preferred that the unthreaded end 16 of the skirt 14 be tapered to facilitate the envelopment of the fish as the tool is turned within the wellbore liner such that the tapered end 16 of the skirt 14 engages the exterior of the tubing string or fish and slips thereupon such that the exposed pin or box end of the reversible tie-back tool directly meshes therewith the threads of the fish, insuring screwing back into the tubing string without damaging either box or pin. Without the tool, the fish would be damaged before strings could be made up pressure tight. It is a further preferred embodiment of the present invention that the central passageway 26 of the main housing 12 be circular and have a similar diameter to the internal diameter of the fish such that continued production therethrough the central passageway 26 in combination with the lost tubing string and the reclamation tubing string turned within the opposite end of the reversible tie-back tool provides an adequate production facility for the wellbore.

The design criteria of the reversible tie-back tool of the present invention is fabricated in any machine shop preferably of 41/40 steel, but any other comparable metallic or rigid material, which provides an adequate tool for combination therewith the lost tubing string fish and the reclamation tubing string lowered from the surface with reversible tie-back tool contained thereon may be utilized. The particular tool dimensions and type threads are designed to fit the requirements of the particular tie-back job required with adequate lubrication and fluid sealing lubricants being placed within the collar threads in order to provide for easy tie-back and pressuring in excess of, for example a l000-pounds pressure such that the wellmay be brought on production without fluid loss thereto the annulus formed between the production tubing and wellbore liner.

Generally, the threading of the reversible tie-back tool of the present invention will involve right-hand turned threads wherein all the threads turn in unison and form a tightening effect as the reclamation tubing string is turned from the drilling rig contained upon the surface such that the main housing is further turned within the skirt threads in order to provide a sufficient tie-in therewith. The box or pin are respectively turned within-the fish and reclamation tubing such that adequate pressuring thereof the tubing string formulated through the combination of the fish, through the reversible tie-back tool, with the reclamation tubing string is provided.

Therefore, through utilization of the reversible tieback tool of the present invention, one isvprovided with a tool which may be used in order to back off a plugged tubing string stuck within a wellbore liner. The tubing string may be backed off, plug removed, completion of v the string is run through the introduction of the reversible tie-back tool to the bottom of the tubing string in order to provide a continuous production tubing string throughout the well without the necessity of incorporating complicated wellbore equipment in order to accomplish the tie-back operation.

While the invention has been described above with respect to certain embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as set forth therein.

Therefore, I claim:

1. A reversible tie-back tool for locating and securing a fish within the liner of a wellbore, which comprises:

a. a skirt having an outside diameter less than the inside diameter of the liner and an inside diameter greater than the outside diameter of the fish and being internally threaded upon one end;

b. a main housing having a central passageway therethrough its axial center connecting each end thereof and an outside diameter similar to that of the threaded skirt and being threaded at two diammetrically opposed positions along its circumferential surface so that either threaded surface may be received by the threads of the skirt, having a threaded box with an outside diameter less than the inside diameter of the skirt turned upon one end of the main housing and a threaded pin having an outside diameter less than the inside diameter of the skirt turned upon the opposing end of the main housing from that of the threaded box, said box and pin being internally and externally threaded, respectively, to receive the threads of thefish, and one end of the main housing being turned within the skirt to form the reversible tie-back tool.-

2. The reversible tie-back tool of claim 1 wherein the unthreaded end of the skirt is tapered to facilitate the envelopment of the fish. I

3. The reversible tie-back tool of .claim 1 wherein the central passageway of the main housing is circular and of a similar diameter to that of the intemal diameter of the fish. v 

1. A reversible tie-back tool for locating and securing a fish within the liner of a wellbore, which comprises: a. a skirt having an outside diameter less than the inside diameter of the liner and an inside diameter greater than the outside diameter of the fish and being internally threaded upon one end; b. a main housing having a central passageway therethrough its axial center connecting each end thereof and an outside diameter similar to that of the threaded skirt and being threaded at two diammetrically opposed positions along its circumferential surface so that either threaded surface may be received by the threads of the skirt, having a threaded box with an outside diameter less than the inside diameter of the skirt turned upon one end of the main housing and a threaded pin having an outside diameter less than the inside diameter of the skirt turned upon the opposing end of the main housing from that of the threaded box, said box and pin being internally and externally threaded, respectively, to receive the threads of the fish, and one end of the main housing being turned within the skirt to form the reversible tie-back tool.
 2. The reversible tie-back tool of claim 1 wherein the unthreaded end of the skirt is tapered to facilitate the envelopment of the fish.
 3. The reversible tie-back tool of claim 1 wherein the central passageway of the main housing is circular and of a similar diameteR to that of the internal diameter of the fish. 